WorldPac (Pack of 4) E Track Fitting with 6.5mm O-Ring O Ring fitting to fit on E or A track Three Plates Base with 5,000 LBs Capcity 6.5mm Diamater, Stainless Steel O Ring 5/32" thick plates held together with two 3/16" rivets Zinc Plated Gold Chromate Finish Base for Corrosion Resistance